1. Field of the Invention
Aspects of the present invention relate to a rechargeable battery. More particularly, aspects of the present invention relate to a rechargeable battery including a current collecting plate having an improved structure.
2. Description of the Related Art
Rechargeable batteries can be repeatedly charged and discharged, unlike primary batteries, which are incapable of being recharged. Low capacity rechargeable batteries composed of a single cell are generally used for portable small electronic devices, such as mobile phones, laptop computers, and camcorders. Large capacity rechargeable batteries composed of a plurality of cells connected in a form of a pack are widely used to drive motors of hybrid electric vehicles.
A rechargeable battery may be manufactured in various forms. Representative forms of a rechargeable battery include a cylindrical form or a quadrilateral form.
Such rechargeable batteries may be serially connected to form a rechargeable battery module to drive a motor for an electric vehicle, which needs a large amount of electric power.
A typical rechargeable battery includes an electrode assembly having an anode and a cathode with a separator interposed therebetween, a case that provides a space to house the electrode assembly, and a cap assembly that closes and seals the case.
In the case of a rechargeable battery formed in a cylindrical shape, an anode uncoated region and a cathode uncoated region where an active material is not coated are formed at the anode and the cathode of the electrode assembly, respectively. The anode uncoated region and the cathode uncoated region are disposed at opposite ends of the electrode assembly.
A cathode current collecting plate is adhered on the cathode uncoated region, and an anode current collecting plate is adhered on the anode uncoated region. Each of the cathode current collecting plate and the anode current collecting plate is electrically connected to the case or the cap assembly to guide the current to the outside. For example, the cathode electrode current collecting plate may be electrically connected to the case, and the anode current collecting plate may be electrically connected to the cap assembly. Alternatively, the cathode electrode current collecting plate may be electrically connected to the cap assembly, and the anode current collecting plate may be electrically connected to the case.
The case acts as a cathode terminal when the cathode current collecting plate is electrically connected to the case. A cap plate of the cap assembly acts as an anode terminal when the anode current collecting plate is electrically connected to the cap assembly.
The cathode and anode current collecting plates are secured to the cathode uncoated region and the anode uncoated region, respectively, by a method such as welding. To increase the current collecting efficiency, the cathode and anode current collecting plates should be in contact with a large area of their respective uncoated region.
However, conventional current collecting plates cannot be fully welded to the uncoated region at edge regions of the current collecting plates, particularly by laser welding because, when a laser is irradiated at the edge regions of the current collecting plates, the laser may deviate from the current collecting plates and may damage the uncoated region of the anode or cathode.
If the uncoated region located at an edge region of an anode or cathode cannot be connected to the current collecting plate, the output of the rechargeable battery may deteriorate since charges collected at the edge regions cannot move to a current collecting plate.
Meanwhile, it is desirable that the centers of each current collecting plates should be consistently aligned with the center of the electrode assembly when the rechargeable battery is assembled. However, consistent alignment is very difficult because the cross-sections of the current collecting plates are smaller than the cross-section of the electrode assembly.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.